"Cocktail trees" are created by grafting together several types of fruit-bearing trees. For example:
Stone fruit salad trees grow peaches, plums, nectarines, apricots and peachcots. Citrus salad trees offer a winter and summer orange, mandarins, lemons, limes, grapefruits, tangelos and pomelos. Multi-apple trees boast between two and four different kinds of apples and multi-nashi trees produce between two and four different kinds of Asian pears.
Why they are popular:
The main advantage of multi-graft plants like fruit salad trees is convenience. Many people do not have room for several large fruit trees in their backyard, but would ideally like to harvest more than one kind of fruit. Different multi-graft techniques work best for different combinations of species. In general, the more closely related the plants, the more successful the graft. Getting a single tree to bear apples, oranges and bananas is probably too problematic a goal to come to fruition.